Swim fin



FIG. 1 is a top and front perspective view of a swim fin showing my new design, the broken lines are for illustrative purposes only and form no part of the claimed design;

FIG. 2 rear perspective showing the bottom rear and also the right side thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a front elevational view thereof;

FIG. 5 is a right side elevational view thereof;

FIG. 6 is a rear elevational view thereof;

FIG. 7 is a left side elevational view thereof; and,

FIG. 8 is a bottom plan view thereof. 

The ornamental design for a swim fin, as shown and described. 